The inventor herein is a pioneer in the area of utility knives, and more specifically in folding utility knives, that are typically used in various trades and by home handymen. The majority of such utility knives typically provide for the use of a single type of cutting blade, typically being the standard quadrilateral-shaped utility blades having upper and lower parallel edges, the lower of which is sharpened to form a cutting edge and of generally longer length than the upper edge. The upper edge is typically unsharpened and has one or more notches designed to index with a holding means mounted in the body of the utility knife. The other two opposed edges are also typically unsharpened, and are generally shorter and angled congruently, but in opposite directions from one another, to provide for a reversible blade having two points.
The following documents represent the closest known prior art at the time of filing of this patent application.
United States Published Patent Application No. 2009/0217536, published Sep. 3, 2009 to Medhurst, the present inventor, and entitled HAND TOOL WITH INTERCHANGEABLE TOOL ELEMENTS, discloses a hand held cutting tool for use with a plurality of different tool elements. One blade is a standard quadrilateral-shaped utility knife blade having upper and lower parallel edges, the lower of which is typically sharpened to form a cutting edge as described immediately above. There are two notches in the unsharpened upper edge. When the conventional utility knife blade is fully inserted in a rearward sliding motion into its respective chamber, and the rocker member is thereafter pivoted to its locked configuration, a tooth on the rocker member engages the rearmost indexing notch utility knife blade to retain the utility knife blade in place. The utility knife blade cannot be slidably moved to more than one in-use position.
U.S. Pat. No. 8,935,855, issued Jan. 20, 2015 to Qui, and entitled UTILITY KNIFE AVOIDING ACCIDENTAL DETACHMENT OF BLADE, discloses a utility knife that a standard quadrilateral-shaped utility knife blade having upper and lower parallel edges, the lower of which is sharpened to form a cutting edge as described immediately above. There are two indexing notches in the unsharpened upper edge. A locking part on a tilting lock rod engages the rearmost indexing notch of the utility knife blade to retain the utility knife blade in place. The utility knife blade cannot be slidably moved to more than one in-use position.
United States Published Patent Application No. 2013/0255087, published Oct. 3, 2013 to Wang, and entitled UTILITY KNIFE WITH REPLACEABLE BLADE, discloses a utility knife with a replaceable blade, comprising a knife handle, a blade holder, a blade and a locking device that locks the utility knife blade in the blade holder. The blade holder and the blade are enabled to switch between a first position and a second position. When the blade holder and the blade are in the first position, the blade is used for cutting operation, and when the blade holder and the blade are in the second position, both the blade holder and the blade are received in the knife handle. A locking member on the locking device engages the rearmost indexing notch of the utility knife blade to retain the utility knife blade in place. The utility knife blade cannot be slidably moved to more than one in-use position.
U.S. Pat. No. 6,148,522, issued Nov. 21, 2000 to Dobandi, and entitled DUAL-BLADE UTILITY KNIFE, discloses a dual blade utility knife that includes double-ended, retractable, separately actuatable cutting blades. When the utility knife cutting blade is inserted into blade holder, the blade is stopped by a blade stop. The end tip of the blade holder fits inside rearmost recessed portion on the blade to hold it firmly in position. The utility knife blade cannot be slidably moved to more than one in-use position.
The inventor has, as an early adaptor of this technology, become aware of the need for further improvements in this area, and has become aware that through the present invention such further improvements are significant and can overcome various problems with the prior art and can meet needs that are apparent in the related art. To this end, it is an object of the present invention to provide an improved folding utility knife.
It is also an object of the present invention to provide an improved folding utility knife wherein the knife blade is slidable to a plurality of in-use positions.
It is also an object of the present invention to provide an improved folding utility knife wherein blade locking mechanism of the knife blade engages each of a plurality of notches in the indexing edge of the knife blade corresponding one each to the plurality of in-use blade positions.
It is also an object of the present invention to provide an improved folding utility knife that can effectively cut through both thin and thick objects by reason of having a larger range of usable cutting edge extendable from the front end of the blade holder than is possible with standard quadrilateral-shaped utility blades available in the prior art.
It is also an object of the present invention to provide an improved folding utility knife wherein the useful life of the cutting blade is longer than in prior art knives due to the availability of extra cutting blade length.
There is thus disclosed according to one aspect of the present invention a folding utility knife comprising a handle and a blade holder mounted on the handle for angular movement relative to the handle between a fully open position and a fully closed configuration. A blade holder locking mechanism is operatively interconnected between the handle and the blade holder for releasably locking the blade holder at the fully open position. A cutting blade extends longitudinally between a first blade end and a second blade end and has a cutting edge extending between the first blade end and the second blade end in opposed parallel relation to an indexing edge. The indexing edge has a first indexing notch, a second indexing notch and a third indexing notch spaced from one another along the indexing edge. A blade locking mechanism has a locking pin mounted on the blade holder for locking engagement with a selected one of the first indexing notch, the second indexing notch, and the third indexing notch to hold fast the cutting blade against longitudinal sliding movement within the blade holder, such that: i) locking engagement of the locking pin with the first indexing notch holds the cutting blade against the longitudinal sliding movement in a first blade position wherein the first end and a first short portion of the cutting edge is exposed for use; ii) locking engagement of the locking pin with the second indexing notch holds the cutting blade against the longitudinal movement in a second blade position wherein the first end and a first intermediate portion of the cutting edge is exposed for use; iii) locking engagement of the locking pin with the third indexing notch holds the cutting blade against the longitudinal movement in a third blade position wherein the first end and a first longer portion of the cutting edge is exposed for use; and such that the cutting blade is releasable from the locking engagement in the first, second and third blade positions to permit removal of the cutting blade from the blade holder and for rotation of the cutting blade through 180 degrees of rotation in a horizontal plane for re-insertion of the first end into the blade holder whereat: iv) locking engagement of the locking pin with the third indexing notch holds the cutting blade against the longitudinal movement in a fourth blade position wherein the second end and a second short portion of the cutting edge is exposed for use; v) locking engagement of the locking pin with the second indexing notch holds the cutting blade against the longitudinal movement in a fifth blade position wherein the second end and a second intermediate portion of the cutting edge is exposed for use; and, vi) locking engagement of the locking pin with the first indexing notch holds the cutting blade against the longitudinal movement in a sixth blade position wherein the second end and a second longer portion of the cutting edge is exposed for use.
The above and other objects, advantages, features and characteristics of the present invention, as well as methods of operation and functions of the related elements of the structure, and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following detailed description and the appended claims with reference to the accompanying drawings, the latter of which is briefly described hereinbelow.